This invention relates to a heat sink for promoting heat dissipation from a large-scaled integrated circuit or the like, and more particularly to a heat sink exhibiting enhanced cooling efficiency and a method for effectively and economically manufacturing the same.
The inventor has made research and development of a heat sink for enhancing heat dissipation of a large-scaled integrated circuit or the like and, as a result, has filed many patent applications. Heat sinks thus proposed by the inventor are each formed by subjecting, for example, an aluminum material to plastic working, to thereby raise a number of fins from a base section. A configuration of the heat sink such as a height of the radiation fins or the like which directly affects cooling performance of the heat sink permits the heat sink to exhibit novelty and originality which are never anticipated from the prior art.
Such a heat sink is mainly used as a heat dissipation element for a CPU of a personal computer or the like. In the market, a personal computer tends to be requested to exhibit a further increased processing speed, therefore, currently an increase in generation of heat from a CPU or the like due to increases in clock frequency and the number of gates is unavoidable.
In order to further enhance heat dissipation efficiency from an electronic component in view of such current circumstances, it is carried out to use a heat sink having a bottom surface area several times as large as an upper surface area of a package of a CPU or the like, which is so constructed that a metal plate made of a metal material increased in thermal conductivity as compared with a material for the heat sink is interposed between the upper surface of the package and a bottom surface of a base plate of the heat sink.
Now, such construction will be described with reference to FIGS. 9A and 9B by way of example. A heat sink 1xe2x80x2 includes a base plate 2xe2x80x2, which is fixedly mounted on a bottom surface thereof with a metal plate 6xe2x80x2 having the same shape as the bottom surface of the base plate 2xe2x80x2 by any suitable techniques such as brazing, screwing or the like. Then, the heat sink 1xe2x80x2 is securely fixed through the metal plate 6xe2x80x2 to an upper surface of a package of an electronic component Exe2x80x2 such as a CPU or the like while being kept in contact with the upper surface of the package.
Such construction permits heat generated from the electronic component Exe2x80x2 to be diffused or dispersed over a whole region of the metal plate 6xe2x80x2 and then transferred to the whole bottom surface of the heat sink 1xe2x80x2, resulting in heat dissipation of the heat sink 1xe2x80x2 being carried out with improved efficiency.
However, the above-described screwing which takes place for fixing of the metal plate 6xe2x80x2 to the bottom surface of the base plate 2xe2x80x2 causes the number of parts for the fixing and the number of steps therefor to be increased, leading to an increase in manufacturing cost of the heat sink. Also, it is highly difficult to carry out the fixing while keeping the whole metal plate 6xe2x80x2 in intimate or close contact with the whole bottom surface of the base plate 2xe2x80x2, to thereby cause loss in heat transfer, resulting in it failing in a satisfactory improvement in performance of the heat sink.
Also, the brazing taking place for the fixing requires a pretreatment prior to the brazing. More particularly, prior to the brazing, it is required to subject a joint surface of the base plate 2xe2x80x2 of the heat sink 1xe2x80x2 made of an aluminum material to a surface treatment such as plating, metal spraying or the like to permit the joint surface of the heat sink to be ready for the brazing. Unfortunately, the pretreatment with respect to the heat sink 1xe2x80x2 having the radiation fins 3xe2x80x2 already formed thereon causes not only a manufacturing cost to be highly increased but a reduction in strength of the radiation fins 3xe2x80x2 and deformation thereof due to softening of the radiation fins 3xe2x80x2 by heating during the brazing.
Further, fixing of the metal plate 6xe2x80x2 to the bottom surface of the base plate 2xe2x80x2 is often carried out by post-attaching the metal plate 6xe2x80x2 to the heat sink 1xe2x80x2 after formation of the heat sink 1xe2x80x2. Unfortunately, this frequently causes inadvertent bending of the radiation fins 3xe2x80x2 which are inherently delicate, leading to a deterioration in yields of the heat sink.
The present invention has been made in view of the foregoing disadvantages of the prior art.
Accordingly, it is an object of the present invention to provide a heat sink which is capable of promoting heat transfer from a heat generating element to the heat sink while realizing a reduction in manufacturing cost of the heat sink and an increase in yields thereof.
It is another object of the present invention to provide a method for manufacturing a heat sink which method is capable of providing a heat sink realizing the above-described object.
In accordance with one aspect of the present invention, a heat sink is provided. The heat sink includes a base plate adaptable to be kept in direct contact with an electronic component which requires that heat be dissipated therefrom during operation thereof and radiation fins arranged so as to project from the base plate. The base plate includes a main base plate section made of a main material of which the radiation fins are made and a base plate section for promoting heat transfer (hereinafter referred to as xe2x80x9cheat transfer promoting base plate sectionxe2x80x9d) made of a heat transfer promoting material different from the material for the main base plate section. The heat transfer promoting material is previously integrated with the main material at a stage at which working of a workpiece is started.
The above-described construction of the heat sink permits heat generated from an electronic component to be diffused or dispersed over the whole heat transfer promoting base plate section and then transferred through the whole main base plate section to the radiation fins, so that the heat sink may be increased in heat dissipation efficiency.
The heat transfer promoting material is previously integrated with the main material at a stage at which working of the workpiece is started. This ensures that the heat transfer promoting base plate section is formed integrally with the main base plate section concurrently with forming of the heat sink, to thereby eliminate parts such as screws or the like for fixing of the heat transfer promoting base plate section to the main base plate section and operation for the fixing, resulting in a manufacturing cost of the heat sink being reduced and inadvertent bending of the radiation fins which are intrinsically delicate being prevented.
In accordance with this aspect of the present invention, a heat sink is provided. The heat sink includes a base plate adaptable to be kept in direct contact with an electronic component which requires that heat be dissipated therefrom during operation thereof and radiation fins arranged so as to project from the base plate. The base plate is constituted by only a heat transfer base plate section made of a heat transfer promoting material. The radiation fins are made of a main material and arranged so as to project from the heat transfer promoting base plate section. The heat transfer promoting material is previously integrated with the main material at a stage at which working of a workpiece is started. The heat sink thus constructed permits heat generated from the electronic component to be efficiently dissipated from the radiation fins.
In a preferred embodiment of the present invention, the main material is aluminum alloy and the heat transfer promoting material is a material having thermal conductivity larger than that of aluminum. Such construction promotes that heat generated from the electronic component is diffused or dispersed over the whole heat transfer promoting base plate section and then transferred through the main base plate section to the radiation fins, to thereby enhance heat dissipation efficiency of the heat sink.
In a preferred embodiment of the present invention, the heat transfer promoting material is selected from the group consisting of copper and an alloy thereof. Such construction permits heat generated from the electronic component to be efficiently dispersed or diffused over the whole heat transfer promoting base plate section.
In a preferred embodiment of the present invention, the main material and heat transfer promoting material are coupled together by techniques selected from the group consisting of brazing, pressure welding by forging, deformation together with intermeshing and any combination thereof. Such construction permits the heat transfer promoting material to be in intimate or close contact with the main material, so that heat generated from the electronic component may be effectively dispersed or diffused over the whole heat transfer promoting base plate section.
In a preferred embodiment of the present invention, the heat transfer promoting material is coupled to the main material by plating the heat transfer promoting material on the main material. Such construction permits the heat transfer promoting material to be in more intimate contact with the main material, so that heat generated from the electronic component may be dispersed or diffused over the whole heat transfer promoting base plate section with enhanced efficiency.
In a preferred embodiment of the present invention, the main material and heat transfer promoting material are formed at a joint portion thereof through which both materials are coupled together with a means for increasing a contact area therebetween. Thus, efficient heat transfer from the heat transfer promoting base plate section to the main base plate section may be ensured.
In accordance with another aspect of the present invention a method for manufacturing a heat sink is provided. The method includes the step of subjecting a workpiece to forging under pressure in a die to form a base plate and radiation fins projecting from the base plate. The workpiece is made of a main material and a heat transfer promoting material having thermal conductivity larger than that of the main material. The radiation fins are constituted of the main material. Also, the base plate may be constituted of the main material depending on a form of the heat sink as desired. The heat transfer promoting material is integrally provided on a surface of the main material opposite to a surface of the main material on which the radiation fins are formed.
The method of the present invention thus constructed permits the heat transfer promoting base plate section to be formed integrally with the main base plate section concurrently with forming of the heat sink, to thereby eliminate parts such as screws or the like for fixing of the heat transfer base plate section to the main base plate section and operation for the fixing, resulting in a manufacturing cost of the heat sink being reduced and inadvertent bending of the radiation fins which are intrinsically delicate being prevented.
In a preferred embodiment of the present invention, the main material and heat transfer promoting material are previously formed integrally with each other by brazing. This ensures that the heat transfer promoting material is kept in intimate or close contact with the main material, so that heat generated from the electronic component may be effectively dispersed over the whole heat transfer promoting base plate section.
In a preferred embodiment of the present invention, the main material and heat transfer promoting material are previously formed integrally with each other by plating of the heat transfer material on the main material. This permits the heat transfer promoting material to be kept in more intimate contact with the main material, so that heat generated from the electronic component may be dispersed or diffused over the whole heat transfer promoting base plate section with enhanced efficiency.
In a preferred embodiment of the present invention, the main material and heat transfer promoting material are previously formed integrally with each other by temporarily coupling the main material and heat transfer promoting material to each other at the time working of the workpiece is started and subjecting at least one of the main material and heat transfer promoting material to plastic deformation, to thereby permit both materials to bite or intermesh with each other. This ensures that the heat transfer promoting material is kept in close contact with the main material, resulting in heat generated from the electronic component being efficiently dispersed over the whole heat transfer promoting base plate section. Also, this permits the main base plate section and heat transfer promoting base plate section of the base plate to be integrally constructed together during forging under pressure, to thereby eliminate a separate step of coupling both sections to each other, leading to a reduction in manufacturing cost of the heat sink.